The present invention relates to a support structure of scaffold pipe, framework construction, and more particularly the invention relates to an improved mud sill that attaches to a base foot plate of a scaffold like framework. The scaffold assembly is constructed from tubular alignments having plural, singular, and vertically arranged rigid horizontal frames. A frame is typically a rectangular construct but can also be triangular in configuration. The other ends of the upright corner post elements of such vertical frames interconnect at two corners. The mud sill is the lowest element for a scaffolding foundation which rests between the lower steel baseplate of screw jack and the ground upon which the scaffolding stands. In order to distribute vertical load on the ground that may shift, the baseplate is typically nailed to a mud sill. The mud sill may be an elongated eight by ten which is disposed under and fastened to a number of parallel baseplates with nails or it can consist of sections of shorter two by ten lumber that is attached to an individual baseplate.
General requirements of OSHA regulations (Section 1926.451c) in connection with the criteria for supporting scaffold provides that the supported scaffold poles, posts, frames, and uprights shall bear on baseplates and sills or other adequate firm foundation.
Scaffolding to support workers above the ground during construction is well-known in the art and many variations have been considered. One very common type of scaffolding used during construction of a wall or other structure includes a set of four uprights, bridged by sets of horizontal support members. Cross-braces extend between pairs of uprights to stabilize the scaffolding. The horizontal support members provide a frame across which a set of planks, typically made of wood, are laid to form a platform upon which workers can stand. As progress is made during construction, the horizontal support members are raised and locked in place at new heights, allowing workers standing atop thereof to work on higher sections of the wall being constructed. Additional uprights can be affixed atop the scaffolding, thus allowing higher levels of horizontal support members and platforms to be put in place.
Scaffolding of this nature is generally ground-based: supported on the ground surface. When supported on the ground surface, the uprights are typically placed atop swivel base screw jacks for leveling the scaffolding. The base of each screw jack typically has a flat baseplate that is nailed to a wood block or an elongated board, i.e. mud sills, that are placed on the ground. The mud sills distribute the weight of the scaffolding over a larger area of the ground than provided by the baseplate ends of the uprights to inhibit the uprights from sinking into the ground.
Although the above-described scaffolding is common, it is time consuming to erect. Also, during construction of such scaffolding, care must be taken to ensure that the uprights firmly rest on the ground and, thereafter, that each horizontal support member is level. As the scaffolding is generally free-standing, it is also important to ensure that the scaffolding is stable. As will be appreciated, slight shifting in the ground can result in unstable scaffolding or, even worse, its collapse. Of particular concern is the time and effort required to attach mud sills to the scaffolding which typically requires that the baseplate be nailed to the wood block or board. Fastening is often done using a minimum number of nails when a maximum of four nails could be used. Additionally, nails are often hammered in only part of the length of the nail and then bent over, leaving the fastening weaker than it would be if the nails were fully inserted by hammering. Another disadvantage to the use of current mud sills is when the scaffolding is taken down or reconfigured, the mud sills are generally removed from the baseplate, which means that additional labor is required to extract the nails and then the nails, discarded as bent nails, are seldom reused.